1. Technical Field
This application relates to a dilator for dilating an opening in the body of a patient for a medical use. More particularly, the invention relates to a loading dilator having a transition balloon at a distal end thereof for use in placement of a medical device, such as a tracheostomy tube, across the body opening.
2. Background Information
The creation of an adequate air passageway is a critical step in maintaining the ability of a seriously ill or injured patient to breathe, or in performing resuscitation on a patient unable to breathe. Endotracheal intubation (the placement of a tube through the nostrils or mouth and into the trachea itself) is a widely-used method for establishing an air passageway. However, in order to establish an optimal air passageway for endotracheal intubation, the trachea, nostrils and/or mouth must normally be free, or at least substantially free, of obstruction. When an obstruction is present, endotracheal intubation is not generally possible, and an alternative passageway for airflow must be established.
The most direct way to provide an air passageway under these circumstances is to form a stoma, or opening, in the tracheal wall. Once formed, a tracheostomy tube is inserted through the stoma. Conventional tracheostomy tubes often include an open distal aperture and a circumferential inflatable cuff. The cuff provides a seal between the tracheal wall and the tracheostomy tube at a location proximal to the distal aperture. The seal prevents the intrusion of blood, tissue or foreign matter into the lower trachea, bronchi and lungs, while permitting complete control and monitoring of the airflow established through the tracheostomy tube, including the provision of positive pressure ventilation. The open distal aperture provides a passageway for air into the lungs of the patient.
Several methods and devices are known for forming, or enlarging, a stoma in a tracheal wall. In one such method, a small opening is initially made in the tracheal wall. A needle is inserted through the small opening, such that the tip of the needle is in the interior space of the trachea. A wire guide is then passed into the trachea through a bore in the needle, and the needle is thereafter withdrawn. Sequentially sized dilators are then advanced over the wire guide to facilitate gradual dilation of the tracheal entrance to an appropriate size.
Recently, a single curved dilator, sold by Cook Incorporated of Bloomington, Ind., under the name BLUE RHINO®, has been developed that avoids the necessity of utilizing multiple dilators. The BLUE RHINO® dilator, so called because its shape resembles the horn of a rhinoceros, has a distal end portion that is curved in a substantially continuous manner, wherein an increasingly larger diameter portion of the dilator may be inserted into the trachea, thereby facilitating clearance of the posterior tracheal wall. Further description of the BLUE RHINO® dilator is provided in U.S. Pat. No. 6,637,435, incorporated by reference herein.
Another method for forming or enlarging a stoma in a tracheal wall for introduction of a tracheostomy tube is described in U.S. Pat. No. 5,653,230, incorporated by reference herein. This method employs a balloon catheter having an inflatable balloon at a distal end of the catheter. The catheter is inserted over a percutaneously inserted wire guide, and the catheter is advanced along the wire guide until the balloon lies across the tracheal wall. The balloon is then inflated to radially dilate a portion of the tracheal wall, thereby forming a stoma in the wall that corresponds to the inflated diameter of the balloon.
Following formation of the stoma by any of the known methods, an introducer/loading dilator is pre-loaded with a tracheostomy tube, and the distal end of the apparatus is passed through the stoma over the previously-inserted wire guide. It is desirable to provide a dilator/tracheostomy tube combination that has a generally smooth transition from dilator to tube, thereby facilitating entry of the distal, or leading, end portion of the tube through the stoma. However, since there are a number of different sizes and manufacturers of tracheostomy tubes, there is a possibility that a significantly-sized lip (resulting from the respective differences in diameter between the loading dilator and the leading end of the tracheostomy tube), may be present at the transition between the loading dilator and the distal end of the tracheostomy tube. One example of a lip L is illustrated in FIG. 1. The presence of a lip at a junction between a smaller diameter loading dilator and a larger diameter tracheostomy tube can hinder insertion of the tracheostomy tube through the stoma, and can increase the trauma experienced by the patient upon insertion of the tube.
It would be desirable to provide a loading dilator that is sized to accommodate tracheostomy tubes having a range of diameters, and that is structured to minimize the transition between the loading dilator and the tracheostomy tube upon insertion of a dilator/tracheostomy tube apparatus.